Clinical Results and Review of Techniques of Thoracic Endoscopic Unilateral Laminotomy with Bilateral Decompression (TE-ULBD) Using the Outside-In Technique for Thoracic Ossified Ligamentum Flavum

Abstract

Objective: Uniportal full endoscopic thoracic endoscopic surgery can be performed through transforaminal and interlaminar approaches. The interlaminar approach is commonly described as thoracic endoscopic unilateral laminotomy for bilateral decompression (TE-ULBD), which is typically indicated for pathologies such as ossified ligamentum flavum and other posteriorly based compressive pathologies. TE-ULBD decompresses the central and lateral recesses of the thoracic spinal canal. Both the outside-in (over the top of ligamentum flavum) and inside-out (under the ligamentum flavum) approaches can decompress the thoracic spinal canal through the uniportal interlaminar endoscopic route.Methods: A retrospective clinical cohort evaluation of patients who underwent TE-ULBD was performed from January 2018 to December 2021 Results: A cohort of 50 cases of TE-ULBD with a mean age of 65 years old were evaluated. The complication rate was 5.4% and the reoperation rate was 2%. Statistically significant mean VAS improvements were found at 1 week, 6 months, and the final follow-up, with changes of 3.95 ± 1.49, 4.95 ± 1.7, and 5.2 ± 1.8 points, respectively. Likewise, the mean Oswestry Disability Index improvements at 1 week, 3 months, and the final follow-up were 33.8 ± 9.05, 40.12 ± 10.38, and 41.92 ± 11.26, respectively (p < 0.001). Significant improvements were found in the cross-sectional area of the spinal canal in the upper endplate, mid-disc, and lower endplate (57.62 ± 50.6, 89.86 ± 55.93, and 64.93 ± 60.91 mm<sup>2</sup>, respectively; p < 0.001). Conclusion: TE-ULBD using the outside-in technique could achieve good clinical outcomes and a low rate of complications in our cohort of patients.